Telephone system.



No. 693,356. Patented Feb 1|, 1902'.

- F. B. snwsme & c. EGN'EB.

TELEPHONE SYSTEM.

(Application filed July 16, 1900.)

(No Model.)

UNITED STATES PATENT OFFICE:

FRANS BIRGER STAFSING, or STOOKHOLM, AND CARL Eemtn, or KLIPPAN, SWEDEN.

TELEPHONE SYSTEEM.

SPEGIFICATKON forming part of Letters Patent No. 693,356, dated February 1 1, 1 902. Application filed July 16, 1900. Serial No. 23,815. (No modeh) To all whom it may concern.-

Be it known that we, FRANS BIRGER STAF- SING, a resident of 5 KOmmendorsgatamStOckholm, Sweden, and CARL EGNER, a resident of Klippan, Sundbyberg, Sweden, subjects of the King of Sweden and Norway, have invented new and useful Improvements in Telephone Systems, of which the following is a specification, reference being had to the drawing accompanying and forming a part hereof.

It is well known that the operators of a telephone-exchange are often obliged to connect their receiving apparatus to the subscribers circuits in order to ascertain whether a discourse has begun or has been finished. This listening, however, is not seldom, to the dotriment of the clearness of the sound transmitted and to the displeasure of the sub scribers, prolonged for too long a time.

The object of the present invention is improvements in telephone systems by means of which the persons using the telephones are enabled to observevwhether any undue listoning takes place or not. the great advantage is also gained that the operators may be spared being unjustly accused of listening.

The invention consists, briefly, in connecting to the circuit of the operators receiver of a usual telephone system an extra source of electric current, in such a manner that extra electric currents are sent out inthe subscribers circuits as soon and as long as the receiving apparatus of the operator at the exchange is coupled to the'said circuits, and in connecting to the subscribers circuit some suitable signaling apparatus which will give I visible \or audible signs when the listening is taking place.

The invention further consists in the special combination of parts hereinafter described and claimed.

In the accompanying drawing the figure shows diagrammatically how this invention may be carried out.

Referring to the drawing, at c and c 1) represent two subscribers circuits of a telephone By this means vanometers, electric bells, or the like-areconnected between neutral points of the sub scribers circuits and the ground, as shown; When the switch (1 is closed, the said battery sends out electric currents which act upon the said indicators, so that signals are obtained which show that the operator is listenmg. I

The invention may be carried out in sev= 'eral other ways well understood by persons skilled in the art to which it appertains without departing from our invention.

Having described our invention, what we claim as new, and desire to secure byUnited States Letters Patent, is'

The combination in a telephone system, of an operators circuit, a switch between said circuit and the line, a source of electric currents connected between a neutral point of the said operators circuit inside the said switch and the ground, a subscribers circuit, and a current-indicator connected between a neutral point of thesaid subscribers circuit and the ground, substantially and for the purpose set forth.

In testimony whereof we have signed our names to this specification in the presence of two subscribing witnesses.

FRANS BIRGER sTAFsINe. CARL EGNER.

' Witnesses:

JOHN J OHANSSON, GERDA LINDKVIST. 

